Sensing devices are typically employed in internal spaces within a turbine. For example, pressure taps are often required on nozzle segments inside a gas turbine. Pressure taps are employed to measure the pressure within internal spaces inside the casing and are connected through the casing to an external pressure measuring device. Particularly, a pressure tap consists of tubing that attaches to a portion of the turbine, e.g., a nozzle segment, and passes through a penetration in the turbine casing to a location external of the casing. The penetration is typically an elongated opening or bore for access to the pressure tap fitting. Parts of the turbine are movable relative to one another during assembly and disassembly necessitating access to the fittings to connect or disconnect the fittings within the casing as applicable. As a specific example, nozzle segments in turbines are typically rotated circumferentially in the turbine casing for assembly/disassembly. This requires the pressure tap tubing to have a pressure fitting between the nozzle segment and the outer turbine casing for tightening/loosening the fitting from outside the turbine casing. There is no access to the pressure fitting from inside the turbine casing because the turbine rotor is in place.
A pressure fitting may comprise a first sub-assembly including a female threaded collar secured to a pressure transmitting conduit, the opposite end of the conduit extending into the cavity whose pressure is to be measured. The fitting also includes a second sub-assembly including a male threaded collar for threaded engagement with the female collar, the male threaded collar also being secured to a conduit extending through the blind opening in the casing to a location external of the casing. When the collars are threaded to one another, a complete pressure transmitting passage from the cavity through the connected conduits to the external pressure sensor is provided. Consequently, a mechanism is necessary to enable tightening/loosening the fitting including connecting/disconnecting the collars relative to one another through a blind opening from a location external of the turbine casing.